1. Field of the Invention
The present invention generally relates to multi-user Multiple Input Multiple Output (MIMO) system. More particularly, the present invention relates to an apparatus and method for effectively selecting the best channels for a plurality of receivers based on effective channel information received from the receivers and sending data simultaneously on the best channels to the receivers in a multi-user MIMO system.
2. Description of the Related Art
In a system beyond the 3rd Generation (3G) system, for example, the 4th Generation (4G) system, both a wireless network and a Core Network (CN) are characterized by ubiquitous and seamless connection, high data rate, openness, and network convergence. The 4G system is designed to be capable of transmitting a large amount of data, aiming at high data rate.
The 4G system will be configured in an integrated form rather than in the form of a single network. That is, satellite networks, Wireless Local Area Network (WLAN), Digital Audio Broadcast (DAB), Digital Video Broadcast (DVB), and other networks will all be merged into the 4G system. Owing to the network integration, data or signals can be sent and received between a transmitter (for example, Base Station (BS)) and a plurality of receivers (for example, Mobile Stations (MSs)) by MIMO. To realize the MIMO technology, the transmitter can be equipped with N transmit antennas and the receivers can also have N receive antennas. As a consequence, data rate can be increased.
Concurrent provisioning of a service to multiple users causes multi-user interference, which can be cancelled by Dirty Paper Coding (DPC). Among DPC techniques, a low-complexity, high-performance Tomlinson-Harashima Precoding (THP) may be used.
A shortcoming of THP is huge feedback information. Since a plurality of receivers send feedback information about individual transmit antennas to a transmitter, the load on the transmitter is increased and overall system performance may be degraded.
Accordingly, there is a need for an apparatus and method for selecting channel in a multi-user MIMO system that can reduce feedback information between receivers and transmitters to reduce the load on the transmitter and avoid degrading overall system performance.